In U.S. Pat. No. 4,235,581, there is disclosed a screw extrusion press which includes barrel temperature control means. The barrel is in sections and is provided with peripheral bores extending axially along the barrel and through which a temperature control medium is circulated. These bores permit the termperature control medium to circulate through annular passages which are provided both in the barrel and in the connecting flanges between the barrel sections.
However, highly abrasive substances are often processed in extruders of this type. Such substances produce wear phenomena on the inner surface of the barrel. After a time, the degree of wear of such surface becomes such as to affect adversely the operation of the press. The entire barrel portion must, in such circumstances, be replaced and this is extremely costly.
These costs are due primarily to the fact that the termperature control means are incorporated in the barrel portion. It would obviously be advantageous if the worn barrel could be replaced without affecting the temperature control means.